catgetmsg.c

unix环境高级编程的源代码

#include    <stropts.h>
#include    "ourhdr.h"

#define    BUFFSIZE    8192

int
main(void)
{
    int                n, flag;
    char            ctlbuf[BUFFSIZE], datbuf[BUFFSIZE];
    struct strbuf    ctl, dat;

    ctl.buf = ctlbuf;
    ctl.maxlen = BUFFSIZE;
    dat.buf = datbuf;
    dat.maxlen = BUFFSIZE;
    for ( ; ; ) {
        flag = 0;        /* return any message */
        if ( (n = getmsg(STDIN_FILENO, &ctl, &dat, &flag)) < 0)
            err_sys("getmsg error");
        fprintf(stderr, "flag = %d, ctl.len = %d, dat.len = %d\n",
                        flag, ctl.len, dat.len);
        if (dat.len == 0)
            exit(0);
        else if (dat.len > 0)
            if (write(STDOUT_FILENO, dat.buf, dat.len) != dat.len)
                err_sys("write error");
    }
}